Power supply



FIG. 1 is a front perspective view from above of a power supply, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a rear side view thereof. 

The ornamental design for a power supply, as shown and described. 